Following to the trend of miniaturization and weight lightening of various electronic devices, photosensitive solder resists which can form micro opening patterns are being used to printed circuit boards, semiconductor package substrates, flexible circuit boards, and the like.
The solder resist, generally, requires developing property, high resolution, insulating property, solder resistance, gold plating resistance, and the like. And, when the solder resist is applied to the semiconductor package substrate and the like, micro unevenness is formed on the surface of the film type solder resist with necessity for securing good adhesive strength with follow-up materials during the process.
Heretofore, a separate surface treatment process such as plasma treatment was applied for forming such micro unevenness on the surface after the film type solder resist, for example DFSR, is formed through the processes of photo-curing, thermo-curing, and so on. However, there was a disadvantage of that total process became complicated and uneconomical because of the additional separate process such as plasma treatment.